The field of the invention is that of home audiovisual networks of the type used to interconnect a plurality of audio and/or video analog and/or digital type terminals (also called devices) so that they can exchange audiovisual signals.
These terminals for example are included among the following list of equipment (which is not exhaustive): television receivers (using satellite, RF channels, cable, xDSL and other means), television sets, video tape recorders, scanners, digital camcorders, digital cameras, DVD readers, computers, personal digital assistants (PDAs), printers, etc.
The home audiovisual network is for example of the high bit rate switched type comprising a certain number of nodes, used especially for the real-time exchange of moving pictures for distribution within a dwelling.
A home audiovisual network according to the invention comprises a plurality of nodes connected by a plurality of physical communication links. These links are for example the type used for two-way data transfers according to the IEEE 1355 standard.
It may be recalled that the IEEE 1355 standard is defined by the IEEE 1355-1995 Standard for Heterogeneous InterConnect (HIC) (low cost low latency scalable serial interconnect) (also known as ISO/IEC 14575 DIS).
Audio and/or video terminals communicate with one another through the nodes to which they are connected. The nodes that form the skeleton of the network comprise especially:                first interface means enabling the connection, through one or more links (for example according to the IEEE 1355 standard), of one or more other nodes;        second interface means used for the connection of one or more analog terminals (namely terminals capable of receiving audiovisual signals in analog form);        third interface means used for the connection (for example through a digital bus according to the IEEE 1394 standard) of one or more digital terminals (namely terminals capable of receiving audiovisual signals in digital form).        
The working of a home audiovisual network of this kind is as follows: a connection is made up, through a plurality of nodes, between a first terminal (or listener) that seeks to receive audiovisual signals and a second terminal (or talker) that can give it these signals.
Some elements of the terminology used hereinafter in the description shall now be specified.
The first terminal mentioned here above is called a destination terminal and the node to which it is connected is called a destination node.
As for the second terminal mentioned here above, two cases may be distinguished.
In a first case, the second terminal is integrated into a node called a “source node”. Thus, it is assumed that the source node comprises means for the reception and/or reading of source signals (originating outside the network) and means for the transmission of these source signals, in the form of the above-mentioned audiovisual signals, to the destination node. In other words, the source node receives and/or reads source signals and introduces them into the home audiovisual network in the form of audiovisual signals. In this first case, the (source) node and the second terminal are the same.
In a second case, the second terminal called an “input terminal” is connected to a node called an “input node”. Unlike the first case, the (input) node and the second terminal are not the same. The input node does not have means for the reception and/or reading of source signals (originating outside the network). The input node receives audiovisual signals coming from the input terminal and introduces them into the home audiovisual network.
The term “input terminal” is understood to mean for example a digital camcorder, a digital camera, a digital output DVD reader or any analog device seen through an analog/digital converter.
It will be noted that a source node can also play the role of an input node if an input terminal is connected to it.
Conventionally, the analog and/or digital terminals of such networks are associated with control devices, generally of the remote control type, enabling their remote control. Thus, a user for example may check the actions of reading, freeze frames or rewinding of a video tape recorder by means of an infrared remote control with a range of about some meters.
Now, in the context of a home audiovisual network of this kind, it is also necessary to give the user the possibility of controlling a remote terminal (typically located in another room of the house or apartment).
Furthermore, one problem that arises for the user is the ability to manage the nodes of the network by remote control.
The invention therefore relates more specifically to the management, within a home audiovisual network, of the control signals designed for the nodes of the network or the analog or digital terminals with which they are connected as well as their conveyance within the network.
To date, there are several types of home installations or networks implementing systems for the conveyance of infrared control signals.
Thus, the U.S. Pat. No. 6,192,399 describes a UTP (unshielded twisted pair) type of network implementing a video server. According to the technique described in the document, when a user wishes to use the video server, infrared commands are conveyed up to this server. The video server centralizes all the commands flowing on the network and, in response, broadcasts the requested information to all the units of the network. At reception of a data packet, each piece of equipment or node of the network ascertains that the received packet is addressed to it and, if this is the case, analyzes its contents.
One drawback of this prior art technique is that it requires the implementation of a centralized control device (in this case the video server) designed to manage all the control signals conveyed on the network and, in response, to broadcast information packets intended for all the units of the network.
The US Patent document U.S. Pat. No. 6,026,150 presents a home telephone network in which each of the devices of the network is assigned an IP (Internet protocol) address. As here above, infrared signal packets are broadcast to all the units of the network and are filtered at each of these destination devices as a function of the IP address that they contain so that only the device to which the packets are addressed carries out an analysis of their contents.
One resulting drawback of this prior art technique is also a drawback of the technique included in the U.S. Pat. No. 6,192,399, i.e. the control signals and the information packets are broadcast to all the units or nodes of the network, including the nodes that are not concerned by such a signal or such a packet.
A resulting drawback of this prior art technique is that such a broadcast of the signals and packets leads to an unnecessary traffic overload within the communications network and further requires that each of the units of equipment of the network should analyze the signals and packets received in order to select those that are addressed to it.
Besides, the exploitation of a home audiovisual network according to the invention requires that each of the terminals of the network should be capable of being identified uniquely especially so that it can be selected at a distance by a user. In other words, the invention also concerns this novel problem of the identification and remote selection of terminals within a home audiovisual network.
Indeed, it will be understood that it may be particularly advantageous for a user of a home audiovisual network to be able to make a selection, from one room of his dwelling, of a terminal located in a neighboring room for example to send it control signals (on, off, pause, etc.) or in order to set up a connection with this terminal.
Thus, a user may wish for example to select a video tape recorder located in his living room to make a connection between this video tape recorder and the television set in his bedroom.
To do so, it is imperative that the terminal which the user wishes to select should be capable of being identified uniquely within the audiovisual network of his dwelling. It is furthermore necessary that this identification should be permanent in time so that, when choosing a given identifier, a user always selects the same terminal, permanently associated with this identifier.
Now, to date, there is no solution enabling this kind of a unique and permanent identification of the terminals of a home audiovisual network and therefore their remote selection by a user.
If the user wishes, from his bedroom, to control the video tape recorder located in his living room, he must move to the living room or at least move until he is within range of a remote control pack associated with the video tape recorder, something that is impractical.
It should be noted that to resolve the problem of the identification of the nodes of a home audiovisual network, it is possible to envisage implementing a network protocol that gives a permanent numbering for all the nodes of the network. However, a protocol of this kind would be highly complex and would have the drawback firstly of not standing up to a powering-off in the network (for example in the event of a current failure or an updating of the topology of the network) and secondly of requiring the implementation of a specific interface enabling the user to know the numbers assigned by the network to each of the nodes.
Furthermore, a technique of this kind would in no way make it possible to uniquely and permanently identify and therefore select the terminals associated with the nodes identified by means of this method. Indeed, the problem of the identification of the nodes of a home audiovisual network is clearly different from the problem of the identification of the terminals of this network.
The IEEE 1394 standard provides for the assigning, to each of the devices complying with this standard, of a universal identifier called the EUI-64. However, the use of the EUI-64 to identify the pieces of equipment of a home audiovisual network would be particularly painstaking and impractical for a user who would be forced, by means of an appropriate man/machine interface, to introduce the 64 bits constituting the identifier of a piece of equipment so as to be able to select it within the network.
Furthermore, this approach is not suited to the identification of the analog terminals of the network which have no EUI-64 identifiers, and therefore does not resolve the aforesaid problem identified by the inventors (namely, the identification and the remote selection of terminals within a home audiovisual network).
A home audiovisual network generally comprises a large number of terminals and therefore also a large number of associated remote controls. When the user wishes to control a particular terminal, he must therefore make a choice, among all the remote controls that he has available, of the one associated with the terminal to be controlled. This is generally a lengthy and painstaking process. To make the use of the network simpler and more user-friendly, it is therefore necessary to reduce the number of remote controls by which the different devices of the network can be controlled.
With regard to the drawback mentioned here above, namely the large number of remote controls used within the network, it has been planned to introduce a universal remote control pack capable of reproducing the functionalities of a plurality of remote controls associated with distinct terminals. For the remote controls possessing a learning mode, the universal remote control and the remote control packs of a television set or video tape recorder are placed face to face and the different keys of the pack are activated so that the universal remote control receives and store the corresponding control signals. The user who wishes to activate his television set or video tape recorder can then activate keys of the universal remote control associated with the memorized signals and the universal remote control emulates the corresponding functions of the remote control pack of the television set or the video tape recorder.
In the context of the home audiovisual network of the invention, it is possible to envisage the use of a single universal remote control which emulates all the functions of all the remote controls associated with the pieces of equipment of the network. An approach of this kind however has several drawbacks.
First, a universal remote control of this kind should have very great storage capacities owing to the large number of remote controls present in the network and hence a large number of functions to be memorized.
Furthermore, the use of a single remote control may be impractical for a user of the home audiovisual network of the invention who will be forced to move about with the universal remote control whenever he goes from one room to another so that he can always control the equipment in the room in which he is located. Moreover, the implementation of a single universal remote control makes it impossible to have simultaneous use of a network by several users located in distinct rooms of the dwelling.
It may be planned to associate a universal remote control to each room of the dwelling and, in each of these remote controls, to store all the commands associated with all the pieces of equipment of the network so that it is possible to use the universal remote control of one room even when moving a terminal from one room of the house to another. However, an approach of this kind will have the drawback, already mentioned here above, of requiring a large storage capacity in each of the universal remote controls. Furthermore, it would require an implementation of a very lengthy and painstaking learning phase, since the user will necessarily have to memorize, in each of the universal remote controls, the totality of the functions proposed by each of the remote controls associated with the equipment of the network. This will be impractical.